1. So first we will create a database helper class by extending SQLiteOpenHelper.
a. In the constructor we need to pass database name and version number. In this example i am creating the DatabaseHelper class as singleton class. So we can get instance of DatabaseHelper using static method getInstance.

  synchronized static DatabaseHelper getInstance(Context context) {
        if (singleton == null) {
            singleton = new DatabaseHelper(context.getApplicationContext());
        }
        return (singleton);
    }

    private DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, SCHEMA_VERSION);
    }

b. For contact table column we are implementing BaseColumns interface. BaseColumns interface providers _id and _count column for us.

    public static final class ContactColumns implements BaseColumns {

        public static final String NAME = "name";

        public static final String PHONE_NUMBER = "phoneNumber";

        public static final String EMAIL = "email";

        public static final String ADDRESS = "address";
    }

c. override the onCreate method of SQLiteOpenHelper. onCreate method will be called when the database is created first time. In this method we will get the instance of SQLiteDatabase. We are using execSQL method of SQLiteDatabase for creating table. execSQL method doesn’t return anything so it should not be used for sql statement that return data.

    @Override
    public void onCreate(SQLiteDatabase db) {
        String s = " (" +
                ContactColumns._ID + " INTEGER PRIMARY KEY, " +
                ContactColumns.NAME + " TEXT, " +
                ContactColumns.PHONE_NUMBER + " TEXT, " +
                ContactColumns.EMAIL + " TEXT, " +
                ContactColumns.ADDRESS + " TEXT" +
                ");";

        db.execSQL("CREATE TABLE " + TABLE_NAME + s);

    }

d. onUpgrade is the second method that we need to override. onUpgrade is called when database needs to be upgraded. Suppose address column was not there in version 1 of contact’s table.This column is added in version 2. In that case when you try to reinstall app with version 2 database onUpgrade method will be called. In onUpgrade method, we will check if old version is 1 , alter the table and add column address. for other versions just drop the table and create again.

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        // Logs that the database is being upgraded
        Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
                + newVersion + ", which will destroy all old data");

        // if (oldVersion == 1) {
        // try {
        // db.execSQL("alter table " + TABLE_NAME
        // + " add column " + "address" +
        // " TEXT;");
        // } catch (SQLException e) {
        // // Shouldn't be needed unless we're debugging and interrupt the
        // // process
        // Log.w(TAG, "Exception upgrading EmailProvider.db from 19 to 20 " +
        // e);
        // }
        // } else {
        // // Drop older table if existed
        // db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        //
        // // Create tables again
        // onCreate(db);
        // }
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);

        // Create tables again
        onCreate(db);

    }

}

2. create ContactData data only class. it will hold all contact information as single entity. We are making ContactData class Serializable because we can send ContactsData object from one activty to another or we can save state of activity with ContactsData object.

public class ContactsData implements Serializable{

    public int mId;
    public String mName;
    public String mPhoneNumber;
    public String mAddress;
    public String mEmail;

    public ContactsData(int id, String name, String phoneNumber) {
        this(id,name,phoneNumber,null,null);
    }
    
    public ContactsData(int id, String name, String phoneNumber,String address, String email) {
        mId = id;
        mName = name;
        mPhoneNumber = phoneNumber;
        mAddress = address;
        mEmail = email;
    }
    
    public ContactsData() {}


}

3. Now we will write methods for database read write operations.

 mDatabaseHelper = DatabaseHelper.getInstance(context);

Add new contact:

a. get writable databse.
b. store column name and value in ContentValues as key value pair
c. use insert method for inserting contacts data with arguments.
d. if values are empty, ContactColumns.NAME(nullColumnHack) column can be null.
e. insert method returns rowId of inserted row.

  // Adding new contact
    public void addContact(ContactsData contact){
        SQLiteDatabase db = mDatabaseHelper.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(ContactColumns.NAME, contact.mName); // Contact Name
        values.put(ContactColumns.PHONE_NUMBER, contact.mPhoneNumber); // Contact phone number
        values.put(ContactColumns.EMAIL, contact.mEmail); // Contact email
        values.put(ContactColumns.ADDRESS, contact.mAddress); // Contact address 
        // Inserting Row
        long rowId = db.insert(DatabaseHelper.TABLE_NAME, ContactColumns.NAME, values);
        db.close();
    }

Getting single contact:

a. get readable database.
b. we will use query (String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit)
c. query method will return resultset as cursor.

// Getting single contact
    public ContactsData getContact(int id) {
        SQLiteDatabase db = mDatabaseHelper.getReadableDatabase();

              Cursor cursor = db.query(
                /* FROM */ DatabaseHelper.TABLE_NAME, 
                /* SELECT */ new String[] {ContactColumns._ID,ContactColumns.NAME, ContactColumns.PHONE_NUMBER}, 
                /* WHERE */ ContactColumns._ID + "=?",
                /* WHERE args */new String[] {String.valueOf(id)}, 
                /* GROUP BY */null, 
                /* HAVING */null, 
                /* ORDER BY */ ContactColumns.NAME+" DESC", 
                /* LIMIT */null);

        if (cursor != null)
            cursor.moveToFirst();
        ContactsData contact = new ContactsData(Integer.parseInt(
                cursor.getString(cursor.getColumnIndex(ContactColumns._ID))),
                cursor.getString(cursor.getColumnIndex(ContactColumns.NAME)),
                cursor.getString(cursor.getColumnIndex(ContactColumns.PHONE_NUMBER)));
        return contact;
    }

Get all contacts:

// Getting All Contacts
    public List getAllContacts() {
        List contactList = new ArrayList();
        // Select All Query
        String selectQuery = "SELECT  * FROM " + DatabaseHelper.TABLE_NAME;

        SQLiteDatabase db = mDatabaseHelper.getWritableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        while (cursor.moveToNext()) {
            ContactsData contact = new ContactsData(Integer.parseInt(
                    cursor.getString(cursor.getColumnIndex(ContactColumns._ID))),
                    cursor.getString(cursor.getColumnIndex(ContactColumns.NAME)),
                    cursor.getString(cursor.getColumnIndex(ContactColumns.PHONE_NUMBER)));
            // Adding contact to list
            contactList.add(contact);

        }
        // return contact list
        return contactList;
    }

Update single contact:

 // Updating single contact
    public int updateContact(ContactsData contact) {
        SQLiteDatabase db = mDatabaseHelper.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(ContactColumns.NAME, contact.mName);
        values.put(ContactColumns.PHONE_NUMBER, contact.mPhoneNumber);

        // updating row
        return db.update(DatabaseHelper.TABLE_NAME, values, ContactColumns._ID + " = ?",
                new String[] {
                    String.valueOf(contact.mId)
                });
    }

Delete single contact:

    // Deleting single contact
    public void deleteContact(ContactsData contact) {
        SQLiteDatabase db = mDatabaseHelper.getWritableDatabase();
        db.delete(DatabaseHelper.TABLE_NAME, ContactColumns._ID + " = ?",
                new String[] {
                    String.valueOf(contact.mId)
                });
        db.close();
    }

contact count:

 // Getting contacts Count
    public int getContactsCount() {
        String countQuery = "SELECT  * FROM " + DatabaseHelper.TABLE_NAME;
        SQLiteDatabase db = mDatabaseHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery(countQuery, null);
        cursor.close();

        // return count
        return cursor.getCount();
    }

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1. What is intent filter in android?

1. Create class for date picker dialog fragment

a. define a public default constructor otherwise it will crash on screen rotation.
b. Define the onCreateDialog() method to return an instance of DatePickerDialog
c. pass OnDateSetListener to the constructor of DatePickerDialog.

public class DatePickerDialogFragment extends DialogFragment {

    private DatePickerDialog.OnDateSetListener mDateSetListener;

    public DatePickerDialogFragment() {

    }

    DatePickerDialogFragment(OnDateSetListener dateSetListener) {
        mDateSetListener = dateSetListener;
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        // Use the current date as the default date in the picker
        final Calendar c = Calendar.getInstance();
        int year = c.get(Calendar.YEAR);
        int month = c.get(Calendar.MONTH);
        int day = c.get(Calendar.DAY_OF_MONTH);

        // Create a new instance of DatePickerDialog and return it
        DatePickerDialog dpd = new DatePickerDialog(getActivity(), mDateSetListener, year, month,
                day);
        // dpd.getDatePicker().setCalendarViewShown(true);
        // dpd.getDatePicker().setSpinnersShown(false);

        return dpd;
    }

}

2. For activating date picker and for displaying selected date we will use button that will look more like spinner with the help of spinner style.

spinner style button

3. use current date as default label of button

  selectDate = (Button) findViewById(R.id.select_date);
  setDate(System.currentTimeMillis());

4. show date picker on click of select_date button.

selectDate.setOnClickListener(datePickerListener);
 OnClickListener datePickerListener = new OnClickListener() {

        @Override
        public void onClick(View v) {
            DialogFragment newFragment = new DatePickerDialogFragment(callback);
        newFragment.show(getSupportFragmentManager(), "datePicker");

        }
    };

date picker

5. Define the callback of DatePickerDialogFragment

 OnDateSetListener callback = new OnDateSetListener() {

        @Override
        public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
            Calendar c = Calendar.getInstance();
            c.set(year, monthOfYear, dayOfMonth);
            setDate(c.getTime().getTime());

        }
    };

6. setDate method for date formating.

  private void setDate(long millisecond){
        int flags = DateUtils.FORMAT_SHOW_DATE | DateUtils.FORMAT_SHOW_YEAR
                | DateUtils.FORMAT_SHOW_WEEKDAY | DateUtils.FORMAT_ABBREV_MONTH
                | DateUtils.FORMAT_ABBREV_WEEKDAY;
        String dateString = DateUtils.formatDateTime(EditContactActivity.this,millisecond, flags);
        selectDate.setText(dateString);

    }

7. We can also use CalendarView for date picker.

        DatePickerDialog dpd = new DatePickerDialog(getActivity(), mDateSetListener, year, month,
                day);
        dpd.getDatePicker().setCalendarViewShown(true);
        dpd.getDatePicker().setSpinnersShown(false);

Calendar view picker

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We can add custom views to actionbar using setCustomView method that takes View as argument. for that first we need to enable DISPLAY_SHOW_CUSTOM option.
In this article we will see how we can create custom actionbar (save and discard actionbar).

1. first we will create custom_actionbar.xml file

2. in this layout we have defined common properties in custom styles.

3. Now in our activity we will inflate this layout and add to actionbar.

  LayoutInflater inflater = LayoutInflater.from(this);

        View actionBarButtons = inflater.inflate(R.layout.custom_actionbar, new LinearLayout(this),
                false);

        View cancelActionView = actionBarButtons.findViewById(R.id.action_cancel);
        cancelActionView.setOnClickListener(mActionBarListener);
        View doneActionView = actionBarButtons.findViewById(R.id.action_done);
        doneActionView.setOnClickListener(mActionBarListener);

        getActionBar().setCustomView(actionBarButtons);
        getActionBar().setDisplayOptions(
                ActionBar.DISPLAY_SHOW_CUSTOM,
                ActionBar.DISPLAY_HOME_AS_UP | ActionBar.DISPLAY_SHOW_HOME
                        | ActionBar.DISPLAY_SHOW_TITLE
                        | ActionBar.DISPLAY_SHOW_CUSTOM);

a. inflate takes xml layout and gives us java object.
b. using setDisplayOptions, we can set multiple display options. like in this example.
we don’t want home as up, home and title, we only want DISPLAY_SHOW_CUSTOM.

4. handle click event of buttons.

  private final View.OnClickListener mActionBarListener = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            switch (v.getId()) {
                case R.id.action_done:
                    onSave();
                    break;

                case R.id.action_cancel:
                    finish();
                    break;
            }
        }

    };

5. declare activity in AndroidManifest.xml file

And here is the screen shot

Custom Actionbar

Related posts:

1. Getting Started With Android
2. What is Intent in android?
3. What is intent filter in android?

So its good to have some idea about development of web services. In this article we will see how easily we can develop RESTful web services using jersey.

Prerequisites:

1. Eclipse jee(http://www.eclipse.org/downloads/)
2. Tomcat 7 (http://tomcat.apache.org/download-70.cgi)
3. Zip of jersey lib (http://jersey.java.net)

Configuration:

1. Start eclipse and select new -> Dynamic web projects.

2. Give the name of the project, if target runtime is not defined, give the path of the downloaded tomcat path and click finish.

3. Unzip the jersey lib and copy all files to the WebContent ->WEB-INF ->lib.
4. Create Resources.java file inside src folder.
5. Now open web.xml file and copy this code.

  contacts
  
    Jersey REST Service
    com.sun.jersey.spi.container.servlet.ServletContainer
    
      com.sun.jersey.config.property.packages
      com.vimviv
    
    1
  
  
    Jersey REST Service
    /rest/*
  

Annotations:
Jersey is based on the java and it uses annotations for making web services development easy.
So first we will see details of some annotations.

@PATH(your_path): sets the path as your_app_name/servlet name/your_path
@POST: HTTP POST request
@GET: HTTP GET request
@PUT: HTTP PUT request
@DELETE: HTTP DELETE request
@Produces(MediaType.TEXT_PLAIN ): it defines in which mime type method will produce data.
@Consumes(type [, more-types ]): it defines in which mime type method will consume data.
@PathParam: it can extract variable param from url path.
@QueryParam: it can extract query param from url

Start some coding:
1. Create new class file contact.java for POJO and add this code.

package com.vimviv;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Contact {

	private int id;
	private String name;
	private String phone;
	
	public Contact() {
		// empty default constructor 
	}
	
	public Contact(int id, String name, String phone){
		this.id = id;
		this.name = name;
		this.phone = phone;
	}
	
	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getPhone() {
		return phone;
	}
	public void setPhone(String phone) {
		this.phone = phone;
	}
	
}

@XmlRootElement: it will help to convert contact object to json/xml data.
Default constructor: don’t forget to add default constructor otherwise it will give error on runtime.

2. add simple getinfo() method and run the project.

package com.vimviv;

import javax.ws.rs.Consumes;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.MediaType;

@Path("contact")
public class Resources {

	@GET
	@Path("getInfo")
	@Produces(MediaType.TEXT_PLAIN)
	public String getInfo() {
		return "Contact details";
	}
	
}

Now we can access getInfo web service with this url

http://localhost:8080/contacts/rest/contact/getInfo

and we will get the output “Contact details”;

3. We can return data in json format

@GET
	@Path("getJsonContact")
	@Produces(MediaType.APPLICATION_JSON)
	public Contact getJsonContact() {
		return new Contact(100,"vimviv","123456789");
	}

url: http://localhost:8080/contacts/rest/contact/getJsonContact
output: {“name”:”vimviv”,”phone”:”123456789″}

You don’t need to do anything just define media type as MediaType.APPLICATION_JSON and return contact object.
4. We can return data in xml format.

@GET
	@Path("getXmlContact")
	@Produces(MediaType.APPLICATION_XML)
	public Contact getXmlContact() {
		return new Contact(100,"vimviv","123456789");
	}
	

url: http://localhost:8080/contacts/rest/contact/getXmlContact

output:

vimviv
123456789

5. user can send ID in url path

	@GET
	@Path("{id}")
	@Produces(MediaType.APPLICATION_JSON)
	public Contact getJsonContactPathId(@PathParam("id")String id) {
		int contactId = Integer.parseInt(id);
		Contact contact;
		if(contactId == 100){
			contact= new Contact(contactId,"vimviv","123456789");
		}else{
			contact= new Contact(contactId,"","");
		}
		return contact;
		
	}

url: http://localhost:8080/contacts/rest/contact/100
output:
{“id”:”100″,”name”:”vimviv”,”phone”:”123456789″}

6. User can also send ID as query param.

@GET
	@Path("getContactWithId")
	@Produces(MediaType.APPLICATION_JSON)
	public Contact getJsonContactQueryId(@QueryParam("id")String id) {
		int contactId = Integer.parseInt(id);
		Contact contact;
		if(contactId == 100){
			contact= new Contact(contactId,"vimviv","123456789");
		}else{
			contact= new Contact(contactId,"","");
		}
		return contact;
		
	}

url: http://localhost:8080/contacts/rest/contact/getContactWithId?id=100

output:
{“id”:”100″,”name”:”vimviv”,”phone”:”123456789″}

7. Like GET method we can also use POST method for consuming json data.

	@POST
	@Path("isContactExist")
	@Consumes(MediaType.APPLICATION_JSON)
	@Produces(MediaType.TEXT_PLAIN)
	public String isContactExist(Contact contact) {
		boolean isExist = false;
		if(contact.getId()==100 && "vimviv".equals(contact.getName())&&"123456789".equals(contact.getPhone())){
			isExist = true;
		}
		return new Boolean(isExist).toString();
		
	}

8. we can see the description of all Web services using
http://localhost:8080/contacts/rest/application.wadl url.

This is just a basic introduction of web service development using jersey. We can do lots of things like saving and fetching contacts from db, etc. For maintaining simplicity i didn’t handled error cases in the code.

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Proximity Sensor: is sensor that can recognize presence of nearby object. we will user this sensor to start voice recognition. So when you take you android device near to your face, proximity sensor will start the voice recognizer.

Voice Recognizer: can convert speech to text. So when you give the voice command, its will return an array of matches and will start TTS.

TTS(Text To Speech): can convert text speech. In this application we will use TTS to listen voice command response.

1. First we will check to see if proximity sensor is available.

SensorManager sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
		Sensor proximitySensor = sensorManager
				.getDefaultSensor(Sensor.TYPE_PROXIMITY);

		if (proximitySensor == null) {
			Toast.makeText(this, "No proximity sensor", Toast.LENGTH_SHORT)
					.show();
		} else {
			sensorManager.registerListener(proximitySensorEventListener,
					proximitySensor, SensorManager.SENSOR_DELAY_NORMAL);
		}

2. We will catch proximity event in onSensorChanged callback method in proximitySensorEventListener.

SensorEventListener proximitySensorEventListener = new SensorEventListener() {

		@Override
		public void onAccuracyChanged(Sensor sensor, int accuracy) {
			// TODO Auto-generated method stub

		}

		@Override
		public void onSensorChanged(SensorEvent event) {
			if (event.sensor.getType() == Sensor.TYPE_PROXIMITY) {
				if (event.values[0] < proximitySensor.getMaximumRange()) {
					startSpeechRecognizer();
				}

			}
		}
	};

3. Start speech recognizer, when any object comes near to mobile.

private static final int VOICE_REQUEST_CODE = 101;
private void startSpeechRecognizer() {
		PackageManager pm = getPackageManager();
		List activities = pm.queryIntentActivities(new Intent(
				RecognizerIntent.ACTION_RECOGNIZE_SPEECH), 0);
		if (activities.size() != 0) {
		Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
		intent.putExtra(RecognizerIntent.ACTION_RECOGNIZE_SPEECH,
				RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
		intent.putExtra(RecognizerIntent.EXTRA_PROMPT, "Voice Command");
		startActivityForResult(intent, VOICE_REQUEST_CODE);
		}else{
			Toast.makeText(this, "Speech Recognizer is not present", Toast.LENGTH_SHORT)
			.show();
		}

	}

Explanation of above code:
queryIntentActivities: will return the list of activities that can handle action ACTION_RECOGNIZE_SPEECH.
ACTION_RECOGNIZE_SPEECH: start implicit activity that can handle action ACTION_RECOGNIZE_SPEECH.
EXTRA_PROMPT: It will show custom message "Voice Command" on voice recognizer activity.

4. We will get result of speech recognizer in onActivityResult callback.

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		if (requestCode == VOICE_REQUEST_CODE && resultCode == RESULT_OK) {
			ArrayList matches = data
					.getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS);
			for (int i = 0; i < commands.length; i++) {
				if (matches.contains(commands[i])) {
					selectedCommand = i;
				}
			}
			if (isTtsInitialized) {
				if (selectedCommand >= 0) {
					tts.speak("you have selected" + commands[selectedCommand]
							+ " command.", TextToSpeech.QUEUE_FLUSH, null);
				} else {
					tts.speak("I am sorry. could you please repeat that.", TextToSpeech.QUEUE_FLUSH, null);
				}

			}

		}
}

Explanation of above code:

requestCode and resultCode: first we will check requestCode and resultCode to insure that onActivityResult is called by speech recognizer with success response.
getStringArrayListExtra: We will get all matches using getStringArrayListExtra. If matches contains our commands, TTS will say that otherwise it will say "I am sorry. could you please repeat that.".

5. We will check to see if TTS is present. First we need to implement OnInitListener and override onInit method.

@Override
	public void onInit(int status) {
		if (status == TextToSpeech.SUCCESS) {
			int result = tts.setLanguage(Locale.US);
			if (result == TextToSpeech.LANG_MISSING_DATA
					|| result == TextToSpeech.LANG_NOT_SUPPORTED) {
				Toast.makeText(this, "Language is not available",
						Toast.LENGTH_SHORT);
			} else {
				isTtsInitialized = true;
			}
		} else {
			Toast.makeText(this, "Initialization failed", Toast.LENGTH_SHORT);
		}

	}

After completion of TTS engine initialization start the TTs.

Intent checkIntent = new Intent();
		checkIntent.setAction(TextToSpeech.Engine.ACTION_CHECK_TTS_DATA);
		startActivityForResult(checkIntent, TTS_REQUEST_CODE);

6. We will get response in onActivityResult.

@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		
		if (requestCode == TTS_REQUEST_CODE) {
			if (resultCode == TextToSpeech.Engine.CHECK_VOICE_DATA_PASS) {
				// success, create the TTS instance
				tts = new TextToSpeech(this, this);
			} else {
				// missing data, install it
				Intent installIntent = new Intent();
				installIntent
						.setAction(TextToSpeech.Engine.ACTION_INSTALL_TTS_DATA);
				startActivity(installIntent);
			}
		}
		super.onActivityResult(requestCode, resultCode, data);
	}

7. Don't forget to unregister proximity sensor listener.

@Override
	protected void onStop() {
		if (sensorManager != null) {
			sensorManager.unregisterListener(proximitySensorEventListener);
		}
		super.onStop();
	}

Instead of just listening the commands we can do lots of things like opening address book, messages, mails, etc. Here is the complete code.

package com.vimviv;

import java.util.ArrayList;
import java.util.List;
import java.util.Locale;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.speech.RecognizerIntent;
import android.speech.tts.TextToSpeech;
import android.speech.tts.TextToSpeech.OnInitListener;
import android.widget.Toast;

public class VoiceCommandActivity extends Activity implements OnInitListener {

	private static final int VOICE_REQUEST_CODE = 101;
	private static final int TTS_REQUEST_CODE = 102;
	private static final String[] commands = { "open", "close", "find" };

	private int selectedCommand = -1;
	private String speachMessage = "I am sorry. could you please repeat that.";
	private boolean isTtsInitialized = false;
	TextToSpeech tts;
	SensorManager sensorManager;
	Sensor proximitySensor;

	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		// check proximity sensor
		sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
		proximitySensor = sensorManager
				.getDefaultSensor(Sensor.TYPE_PROXIMITY);

		if (proximitySensor == null) {
			Toast.makeText(this, "No proximity sensor", Toast.LENGTH_SHORT)
					.show();
		} else {
			sensorManager.registerListener(proximitySensorEventListener,
					proximitySensor, SensorManager.SENSOR_DELAY_NORMAL);
		}
		
		//check for TTS data
		Intent checkIntent = new Intent();
		checkIntent.setAction(TextToSpeech.Engine.ACTION_CHECK_TTS_DATA);
		startActivityForResult(checkIntent, TTS_REQUEST_CODE);

	}

	SensorEventListener proximitySensorEventListener = new SensorEventListener() {

		@Override
		public void onAccuracyChanged(Sensor sensor, int accuracy) {
			// TODO Auto-generated method stub

		}

		@Override
		public void onSensorChanged(SensorEvent event) {
			// TODO Auto-generated method stub

			if (event.sensor.getType() == Sensor.TYPE_PROXIMITY) {
				if (event.values[0] < proximitySensor.getMaximumRange()) {
					startSpeachRecognition();
				}

			}
		}
	};

	private void startSpeachRecognition() {
		// Check to see if a recognition activity is present
				PackageManager pm = getPackageManager();
				List activities = pm.queryIntentActivities(new Intent(
						RecognizerIntent.ACTION_RECOGNIZE_SPEECH), 0);
				if (activities.size() != 0) {
					Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
					intent.putExtra(RecognizerIntent.ACTION_RECOGNIZE_SPEECH,
							RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
					intent.putExtra(RecognizerIntent.EXTRA_PROMPT, "Voice Command");
					startActivityForResult(intent, VOICE_REQUEST_CODE);
				} else {
					Toast.makeText(this, "Recognizer not present", Toast.LENGTH_SHORT)
					.show();
				}

		

	}
	
	// Initialization response of TTS engine
	@Override
	public void onInit(int status) {
		if (status == TextToSpeech.SUCCESS) {
			int result = tts.setLanguage(Locale.US);
			if (result == TextToSpeech.LANG_MISSING_DATA
					|| result == TextToSpeech.LANG_NOT_SUPPORTED) {
				Toast.makeText(this, "Language is not available",
						Toast.LENGTH_SHORT);
			} else {
				isTtsInitialized = true;
			}
		} else {
			Toast.makeText(this, "Initialization failed", Toast.LENGTH_SHORT);
		}

	}

	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		if (requestCode == VOICE_REQUEST_CODE && resultCode == RESULT_OK) {
			ArrayList matches = data
					.getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS);
			for (int i = 0; i < commands.length; i++) {
				if (matches.contains(commands[i])) {
					selectedCommand = i;
				}
			}
			if (isTtsInitialized) {
				if (selectedCommand >= 0) {
					tts.speak("you have selected" + commands[selectedCommand]
							+ " command.", TextToSpeech.QUEUE_FLUSH, null);
					selectedCommand = -1;
				} else {
					tts.speak(speachMessage, TextToSpeech.QUEUE_FLUSH, null);
				}

			}

		}
		if (requestCode == TTS_REQUEST_CODE) {
			if (resultCode == TextToSpeech.Engine.CHECK_VOICE_DATA_PASS) {
				// success, create the TTS instance
				tts = new TextToSpeech(this, this);
			} else {
				// missing data, install it
				Intent installIntent = new Intent();
				installIntent
						.setAction(TextToSpeech.Engine.ACTION_INSTALL_TTS_DATA);
				startActivity(installIntent);
			}
		}
		super.onActivityResult(requestCode, resultCode, data);
	}

	@Override
	protected void onStop() {
		if (sensorManager != null) {
			sensorManager.unregisterListener(proximitySensorEventListener);
		}
		super.onStop();
	}

	
}

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3. What is intent filter in android?

In this post we will see, how does implicit intent work?
According to google intent filter is “To inform the system which implicit intents they can handle”

e.g. you have more that one activities in your application and you know that there is no “main” method in android application. So how activity launcher will know that which activity to start first.

For that we specify a intent filter.

intent filter with “android.intent.action.MAIN” action and “android.intent.category.LAUNCHER” category tells to launcher to launch HomeActivity.

implicit Intent is luxury provided by android. You just need to know, what do you want to perform. you don’t bother who is going to perform and how that activity is going to perform.(there will be a problem, if no activity is there to perform your task)

When will you specify intent filter?
if you think, any other application can use your activity to perform some task, specify a intent filter for that. You can be a performer using intent filter.

For example, you have created a activity that can display image and you think that other applications also use your activity to view images.

1. specify intent filter like this.

In the above code we can see that intent-filter has following properties.
a. action: type for which this activity will respond for.Like this activity will respond for view action.
b. category: implicit intents are divided in categories.Like this activity is in default category.
c. data: Specify more information about intent-filter. Like this activity will handle file of mimeType “image/*”.

2. Now you need to display image in your activity.

public class MyImageViewerActivity extends Activity {
	
	TextView textView;
	ImageView imageView;
	
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Intent intent = getIntent();
        Uri uri = intent.getData();
        
        textView = (TextView) findViewById(R.id.textView);
        imageView = (ImageView) findViewById(R.id.imageView);
        
        if(uri != null){
        	imageView.setImageURI(uri);
        	textView.setText(uri.getPath());
        }
        
        
    }
}

using getData() we will get the path of the image and we will use that path to display image.

3. When you install this application in your device and click on any image file, you will see a choice dialog that offer you to select between default application and your application. Just select your application to see the image.

4. Just select your app to view image:

When will you call implicit intent?
If you think that any other activity is available in device for handling your application’s specific task, just use the implicit intent to call that activity.

For example, if you want to open a browser to render URI. You can use implicit intent to call browser.

Uri uri = Uri.parse( "http://blog.vimviv.com" );
startActivity(new Intent(Intent.ACTION_VIEW, uri));

In above example we can see that we have a uri and we want to view content of that uri. We don’t need to know that which activity is going to render this uri.

Some more examples of intent filters.
a) intent filter for app launcher

b)intent filter for image view.

c)intent filter for image send:

d) intent filter for custom uri:

e) intent filter for sms:

f)intent filter phone dial:

Some examples for calling implicit intents:
a) start contacts activity:

Intent contacts = new Intent();
              contacts.setAction(android.content.Intent.ACTION_VIEW);
              contacts.setData(People.CONTENT_URI);
              startActivity(contacts);

b) install an app:

Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(new File(Environment.getExternalStorageDirectory() + "app.apk")), "application/vnd.android.package-archive");
startActivity(intent);  

c) uninstall an app:

Uri packageUri = Uri.parse("package:com.vimviv");
            Intent uninstallIntent =
              new Intent(Intent. ACTION_DELETE, packageUri);
            startActivity(uninstallIntent);

d) start sms application:

Intent sendIntent = new Intent(Intent.ACTION_VIEW);         
sendIntent.setData(Uri.parse("sms:"));

We can also search for a matching intent:

final PackageManager packageManager = context.getPackageManager();
    final Intent intent = new Intent(action);
    List list =
            packageManager.queryIntentActivities(intent,
                    PackageManager.MATCH_DEFAULT_ONLY);
    return list.size() > 0;

So help others by creating re-usable activities.

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• what is intent in android and what is intent filter in android (2)
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• what is intentfilter in android (2)

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@Override
    public String toString() {
    	return super.toString();
    }

In the above example code,
@Override: gives the information that toString() method is overridden from Object class.
In this post we will create custom annotations.

1. First we will create a custom annotation for Database table name.

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface DatabaseTable {

	String tableName();
}

Explanation of above code:
@interface: We can see in the above code is similar to interface declaration. @Retention(RetentionPolicy.RUNTIME): We need this annotation type at runtime. We are using RetentionPolicy.RUNTIME.
@Target(ElementType.TYPE): Indicates that this annotation type will be used to annotate class declaration

2. Next we will create another annotation for column names.

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface DatabaseField {

	String columnName() default "";
	String columnType();
	boolean canBeNull() default true;

}

Explanation of above code:
@Target(ElementType.FIELD): Indicates that this annotation type will used to annotate fields declarations.
default: is used to assign default value.

3. We will create UserInfo class that we want to save in database.

@DatabaseTable (tableName = "user")
public class UserData {

	@DatabaseField (columnName = "first_name", columnType ="TEXT")
	private String firstName;
	@DatabaseField (columnName = "last_name", columnType ="TEXT")
	private String lastName;
	@DatabaseField (columnName = "age", columnType ="INTEGER")
	private int age;

}

4. Create query for create table.

public String createTableQuery(Class clazz){
		DatabaseTable annot = (DatabaseTable) clazz.getAnnotation(DatabaseTable.class);
		String table = annot.tableName();
		Field[] fields = clazz.getDeclaredFields();
		StringBuilder sb = new StringBuilder("CREATE TABLE ").append(table).append(
						" (_id integer primary key");
				for (Field field : fields) {
					DatabaseField fieldAnnot = (DatabaseField) field.getAnnotation(DatabaseField.class);
					String columnName = fieldAnnot.columnName();
					String columnType = fieldAnnot.columnType();
					sb.append(", ").append(columnName).append(" ").append(columnType);
				}
				sb.append(")");
				return sb.toString();
		}

5. We will call this method like this

String sqlQuery = createTableQuery(UserInfo.Class);

Complete implementation of ORM(object relational mapping) is complex. You can check OrmLite – Lightweight Object Relational Mapping (ORM) Java Package for complete annotation based ORM implementation.

We can also search at run time about annotated classes.

public static List getModels(Context context, String packageName)
			throws IOException, URISyntaxException, ClassNotFoundException,
			NameNotFoundException {

		String apkName = context.getPackageManager().getApplicationInfo(packageName, 0).sourceDir;
		DexFile dexFile = new DexFile(apkName);
		PathClassLoader pathLoader = new PathClassLoader(apkName, Thread.currentThread().getContextClassLoader());
		DexClassLoader classLoader = new DexClassLoader(apkName,
				new ContextWrapper(context).getCacheDir().getAbsolutePath(),
				null, pathLoader);
		List classes = new ArrayList();
		Enumeration entries = dexFile.entries();

		while (entries.hasMoreElements()) {

			String entry = (String) entries.nextElement();

			if (entry.startsWith(packageName)) {
				Class entryClass = classLoader.loadClass(entry);
				if (entryClass != null) {
					Annotation[] annotations = entryClass.getAnnotations();
					for (Annotation annotation : annotations) {
						if (annotation instanceof DatabaseTable) {
							classes.add(entryClass);
						}
					}
				}
			}
		}

		return classes;
	}

This was a small example of custom annotation. We can use custom annotations in a lots of ways like configuration, unit testing, etc.

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 private void checkLocationProviders(){
	    //String provider = Settings.Secure.getString(getContentResolver(),Settings.Secure.LOCATION_PROVIDERS_ALLOWED);
	       if(lm.isProviderEnabled(LocationManager.GPS_PROVIDER)){
	    	   
	    	   Toast.makeText(EnableLocationActivity.this, "GPS provider Enabled: ",Toast.LENGTH_LONG).show();
	        
	       }else if(lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER)){
	    	   
	    	   Toast.makeText(EnableLocationActivity.this, "Network provider Enabled: ",Toast.LENGTH_LONG).show();
	    	   
	       }else{
	    	   AlertDialog.Builder builder = new AlertDialog.Builder(this);
	    	   builder.setMessage("Location providers are not available. Enable GPS or network providers.")
	    	          .setCancelable(false)
	    	          .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
	    	              public void onClick(DialogInterface dialog, int id) {
	    	            	  Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
	    	   	          startActivityForResult(intent, 1);
	    	              }
	    	          })
	    	          .setNegativeButton("No", new DialogInterface.OnClickListener() {
	    	              public void onClick(DialogInterface dialog, int id) {
	    	            	  EnableLocationActivity.this.finish();
	    	              }
	    	          }).show();
	    	   
	    	   
	       }

	   }
	   
	   @Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		   checkLocationProviders();
	super.onActivityResult(requestCode, resultCode, data);
	}

Explanation of above code.
1. First we need to create LocationManager.
LocationManager lm = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);

2. using isProviderEnabled Check location providers are already enabled or not.

3. If location providers are not enabled, ask user to enable location providers and launch location settings activity.

4. Using onActivityResult check user has changed location settings or not.

5. Dont forget to add user permission to AndroidMenifest.xml file.

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using java code

EditText editText = new EditText(context);

or using XML

Single-line EditText:

Single-line EditText means if you press “enter key” on EditText,focus will go to the next widget. Default behavior of EditText is multi-line.It means if you press “enter key”, a new line will add to the EditText.
using android:singleLine=”true” property you can make single-line EditText. But this property is now deprecated.
So if you add any inputtype property, EditText will become single-line EditText.
e.g. android:inputType=”text”

Multi-line EditText:
There are two properties are available for multi-line Edittext.
a. android:lines:
Using “lines” property you can specify height of edittext in terms of lines.
e.g. android:lines = “3″ means only 3 lines will be visible in EditText and for 4rth line, you have to scroll vertically.

android:lines

android:inputType
Using the inputType property we can restrict use to enter the correct data.
e.g.

b.android:maxLines
In the above example user can enter only numbers in the EditText widget. If you specify a inputType, EditText will become single line.
using maxLines property you can specify the maximum height of the EditText.
e.g.android:maxLines=”3″ means first only single line will be visible and when you press “enter key”, EditText’s height will expend till the maxLines.

android:maxLines

android:maxLine-1

Gravity:

gravity

Read-only EditText:
Sometimes we need to disable EditText. For that we can use “editable” and “enabled” properties of EditText.

disable

Hint(Watermark) in EditText:
If you are using “hint” property of EditText, a small description of field will be visible inside field and if user clicks on EditText, it disappears and user is free to write something in it. So there is no need of label for EditText, if you are using “hint” property.

android:hint

or from java code

editText.setHint("Enter you name");

Error popup in edittext:
Sometimes user entered invalid data in the EditText and you want to notify user that you have entered an invalid data. In this type of case you can use setError() method of EditText. It will show small popup of the error message.

setError

	
editText.setError("Invalid Input");

Hide soft keyboard:
Sometimes you want to hide soft keyboard on some action. You can do this using this code.

InputMethodManager imm = (InputMethodManager)getSystemService(INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(getWindowToken(), 0);

If in an activity first focus is on EditText, soft keyboard will appear on activity launch. If you don’t want this, you can use this code.

Listen IME key events and enter key:

editText.setOnEditorActionListener(new OnEditorActionListener() {

			@Override
			public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
				if(event!=null && event.getAction()==KeyEvent.ACTION_DOWN){
					//Handle enter key
					return true;
				}
				if(actionId == EditorInfo.IME_ACTION_NEXT){
					//Handle IME NEXT key
					return true;
				}
				if(actionId == EditorInfo.IME_ACTION_DONE){
					//Handle IME DONE key
					return true;
				}
				return false;
			}
		});

android:layout_weight
using layout_weight we can specify the ratio of the size of the child items in the layout.
e.g.

layout_weight

Drawable:
Best thing about android widgets are, you can easily customize them. And for customization you no need to rush codes in the layout xml. So create a drawable xml in the drawable folder
e.g.

drawable

Selector:
EditText can be in different states like focused, disabled, pressed, etc. You can see in the previous example EditText will look same in all states.So if you want to give different looks to EditText for different states. you need to create selector xml.

I will keep update this article because there are lots of things that we can do with EditText widget. If you want to suggest something to improve this post, your comments are always welcome here.

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Intent intent = new Intent(FirstActivity.this,SecondActivity.class);
startActivity(intent);

Implicit Intents: Instead of giving name of the intent you tell the system what you want to perform and system will find suitable activity for your task.
e.g.

intent = new Intent(Intent.ACTION_VIEW,
Uri.parse("http://www.vimviv.com"));
startActivity(intent);

Some example of explicit intents:
1. Start Activity:

Intent intent = new Intent(FirstActivity.this, SecondActivity.class);
startActivity(intent);

2. Get result from activity:

a. FirstActivity.java

public class FirstActivity extends Activity {
	
	Button button;
	private static final int REQUEST_CODE = 10;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        LinearLayout ll = new LinearLayout(this);
        button = new Button(this);
        ll.addView(button);
        setContentView(ll);
        button.setText("Call Second Activity");
        button.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				Intent i = new Intent(FirstActivity.this, SecondActivity.class);
				i.putExtra("data", "Hi from First Activity");
				// Set the request code to any code you like, you can identify the
				// callback via this code
				startActivityForResult(i, REQUEST_CODE);
				
			}
		});
    }
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    	if (resultCode == RESULT_OK && requestCode == REQUEST_CODE) {
			if (data.hasExtra("result")) {
				String message = data.getExtras().getString("result");
				Toast.makeText(FirstActivity.this, message, Toast.LENGTH_SHORT).show();
			}
		}
    }
}

Explanation of above code is as below:
setContentView: we have added button to linear layout and after that linear layout to activity.
putExtra: using startActivity we are launching SecondActivity and with putExtra method we are sending data also.
onActivityResult: When Second Activity will finish it will call the onActivityResult method of FirstActivity.

b. SecondActivity.java

public class SecondActivity extends Activity{

	Button button;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		LinearLayout ll = new LinearLayout(this);
		button = new Button(this);
		ll.addView(button);
		setContentView(ll);
		button.setText("back");
		String message = getIntent().getExtras().getString("data");
		Toast.makeText(this, message, Toast.LENGTH_SHORT).show();
		button.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				finish();

			}
		});
	}

	@Override
	public void finish() {
		Intent data = new Intent();
		data.putExtra("result", "Hi from second activity");
		setResult(RESULT_OK, data);
		super.finish();
	}
}

Explanation of above code is as below:
getExtras: Using the getExtras method we are fetching of data sent by FirstActivity.
finish() :finish method will remove SecondActivity from the display stack and send data to the FirstActivity.

3. Start Service:

Intent intent=new Intent("com.vimviv.service.serviceClass");  
startService(intent);

implicit intents examples:

1. make a call:

Intent callIntent = new Intent(Intent.ACTION_CALL, Uri.parse(“1234567890”));
startActivity(callIntent);

2. Launch google map

intent = new Intent(Intent.ACTION_VIEW,
Uri.parse("geo:37.423156,-122.084917?z=19"));
startActivity(intent);

3. email client:

final Intent emailIntent = new Intent(android.content.Intent.ACTION_SEND);

emailIntent .setType("plain/text");
emailIntent .putExtra(android.content.Intent.EXTRA_EMAIL, newString[]{"yourmail@website.com"});
emailIntent .putExtra(android.content.Intent.EXTRA_SUBJECT, mySubject);

emailIntent .putExtra(android.content.Intent.EXTRA_TEXT, myBodyText);

startActivity(Intent.createChooser(intent, "Send mail));

4. start SMS app:

Intent sendIntent = new Intent(Intent.ACTION_VIEW);        
sendIntent.setData(Uri.parse("sms:"));
sendIntent.putExtra("sms_body", x);

5. To start a search in the Internet:

Intent intent = new Intent(Intent.ACTION_WEB_SEARCH );
intent.putExtra(SearchManager.QUERY, "Android");
startActivity(intent);

For implicit intents read my next post What is intent filter in android?

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